An analogue display device of this type is fitted to the timepiece that is disclosed in JP Patent No. 5702881. This patent discloses and shows a motion work with planetary gears for driving the minute hand and hour hand. For this purpose, it comprises a drive arbour carrying the minute hand at the top end thereof and a drive pinion at the bottom end thereof, the drive pinion meshing with a drive wheel. The drive arbour is provided with a central pinion that is inserted axially between an hour wheel, which is provides for carrying the hour hand, and the drive pinion. The central pinion meshes with two planet pinions, which mesh with a fixed crown with an inner toothing. The mobile axes of rotation of the planet pinions are extended upwards via posts which are respectively received in complementary housings of the hour wheel, so that the rotation of the planet pinions about the drive arbour causes the hour wheel to rotate clockwise.
Of course, the gear reduction between the central pinion and the planet pinions is chosen to obtain the ratio 1:2 between the number of revolutions completed by the hour hand and the number of revolutions completed by the minute hand.
This type of motion work has the advantage of being very compact axially. However, the method of driving the hands remains conventional, i.e. it relies on an hour wheel that has to be mounted on the drive arbour of the minute hand by indenting. The minute hand is driven onto its drive arbour and the hour hand is driven onto the hour wheel. This type of motion work thus requires relatively complex assembly operations.
CH Patent No. 664 468 discloses and shows a timepiece wherein a day/night indicator disc forms the cage of a differential gear which carries the planet pinions meshed with a planetary wheel secure to the hour wheel.
This timepiece has the same type of drawbacks as those previously mentioned, since the hands and the planetary wheel are still mounted on an hour wheel in a conventional manner, which makes the assembly operations relatively complex. Moreover, the structure disclosed in this patent does not allow the display member carrying the planet pinions to be arranged above the dial because of axial space problems and because of the presence of a complex correction mechanism.
It is thus an object of the present invention to improve the construction of this type of analogue display device by simplifying it.